docs: def read_vocab_file(file_path):
    """Reads a vocab file to memeory.
  
    Args:
      file_path: Each line of the vocab is in the form "token,example_count"
  
    Returns:
      Two lists, one for the vocab, and one for just the example counts.
    """
    with file_io.FileIO(file_path, 'r') as f:
      vocab_pd = pd.read_csv(
          f,
          header=None,
          names=['vocab', 'count'],
          dtype=str,  # Prevent pd from converting numerical categories.
          na_filter=False)  # Prevent pd from converting 'NA' to a NaN.
  
    vocab = vocab_pd['vocab'].tolist()
    ex_count = vocab_pd['count'].astype(int).tolist()
  
    return vocab, ex_count